A device (hereinafter referred to as “log generation device”) that generates a log message indicating generation of a predetermined event and transmits the generated log message to another device is used in various fields. A monitoring camera that notifies a server of a central monitoring center when a suspicious person is detected is an example of such a log generation device.
As a data format of the log message, for example, a text format is adopted. Syslog, which describes a log message in ASCII, is an example of such a log message.
However, since the text format log message (hereinafter referred to as “text log”) has a relatively large data size, consumption of communication resources between log generation device and a device that receives the log message (hereinafter referred to as “log collection device”) becomes a problem. In particular, in a case where one log collection device collects log messages from a large number of log generation devices via a common communication line, in a case where a communication band between the log generation device and the log collection device is narrow, or in a case where a transmission amount of the log message is large, the performance of the entire system may be degraded. In addition, in order to avoid such degradation in performance, the number of log generation devices that can be managed by one log collection device is limited.
Therefore, in a side of the log generation device, it is considered that a lexicographic compression for compressing the log data from data of the text log (hereinafter referred to as “log data”) alone is performed, the log data is converted into log data of which the size is compressed, and the log data is transmitted to the log collection device. As such a technique, for example, there is the lexicographic compression (LZW) described in PTL 1. The log collection device performs the decompression of the log data based on the compressed log data alone and restores original log data. Accordingly, it is possible to alleviate the problem described above of consumption of communication resources.
By the way, depending on log generation device, there is a case where it is difficult to have sufficient process capability to perform the lexicographic compression. Therefore, it is desirable to have a technique for enabling low-load text log transmission in a state where an increase in the processing load of the log generation device is suppressed.
An object of this disclosure is to perform at low load transmission of text logs in a case where an increase in the processing load of the log generation device is suppressed.